(a) Field of the Invention
The present invention relates to a joining structure of a plastic material and a metal material.
(b) Description of the Related Art
Recently, in accordance with a trend toward high strength and weight reduction of a vehicle body, a steel sheet such as ultra-high tensile steel, a nonferrous metal plate such as aluminum or magnesium, and a plate made of a plastic material such as carbon fiber reinforced plastic (CFRP) or glass fiber reinforced plastic (GFRP) have been frequently used as a material of the vehicle body.
Among others, since the plastic composite material has excellent strength, elasticity, lightweight property, and stability, the plastic composite material has been highlighted as one of the main materials used in aviation and vehicle industries. For example, in the related arts, it is expected that the subsequent use of the plastic composite material will be further expanded and a manufacturing amount thereof will be also promptly increased.
The plastic composite material has been obtained by impregnating plastic resins in carbon fibers or glass fibers, followed by curing. For example, the plastic composite material may be manufactured by manufacturing the carbon fibers or the glass fibers in a winding shape or a woven fabric shape and then impregnating the carbon fibers or the glass fibers in the plastic resins, followed by curing. Since plastic resins have excellent hardness but are easily broken because tensile strength is poor and the carbon fibers have high tensile strength but do not have bending repulsive power, the plastic composite material may be manufactured by combining the plastic resins and the carbon fibers.
Meanwhile, in order to manufacture the aforementioned plastic composite material as a plate and apply the plastic composite plate to the vehicle body, the plastic composite plate and the metal plate may be joined, but due to distinct physical properties of the two materials, laser welding or spot welding may not be properly performed.
Therefore, in a certain example of the related arts, the dissimilar material plastic composite plate and the metal plate may be joined by a very limitative joining mode, such as a bonding mode using an adhesive or a mechanical joining mode using engagement parts.
Among the modes, examples of the mechanical joining mode of the plastic composite plate and the metal plate using the engagement parts may include a rivet joining technology using a self-piercing rivet. In the mechanical joining technology using the self-piercing rivet, a shape of a joined portion is almost similar to that of spot welding, and thus a design change of the joined portion of the plastic composite plate and the metal plate may be minimized.
In the aforementioned mechanical joining technology using the self-piercing rivet, the plastic composite plate and the metal plate may be joined by allowing the self-piercing rivet to pierce through the plastic composite plate by punching pressure, followed by pressing onto the metal plate and plastic deformation.
However, in the mechanical joining technology using the self-piercing rivet, the self-piercing rivet pierces through the plastic composite plate as it is, and the metal plate is combined with the plastic composite plate while being simply in contact with the plastic composite plate. Accordingly, the periphery of the self-piercing rivet pierced portion of the plastic composite plate may be damaged and joining force of the plastic composite plate with respect to the metal plate may deteriorate.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.